Where does “表外字” come from?

表外字 (Japanese) comes from Japanese 字, from Middle Chinese 字 — letter, symbol, character; character.

表外字 (Japanese): Kanji characters outside of the jōyō kanji and jinmeiyō kanji lists. For example, 攪 and its shinjitai form, 撹

Definitions

  1. Kanji characters outside of the jōyō kanji and jinmeiyō kanji lists. For example, 攪 and its shinjitai form, 撹

Ancestry of “表外字”, step by step

表外字 traces back through 3 separate lines of ancestry.

via Japanese 字

StepLanguageWordMeaning
1Japanese字letter, character; handwriting, penmanship; a...
2Middle Chinese字letter, symbol, character; character

via Japanese 外

StepLanguageWordMeaning
1Japanese外(the) outside
2Middle Chinese外—

via Japanese 表

StepLanguageWordMeaning
1Japanese表surface; face (visible side of an object)
2Middle Chinese表—
Every word from Middle Chinese 字 →Every word from Japanese 字 →